Electric wave translation system



June 9, 1931. R. A. HEISING 1,803,894

ELECTRIC WAVE TRANSLATION SYSTEM Filed April 29, 1924 Patented June 9, 1931 UNETED STATS PATENT QFFEQE RAYDIOND A. HEISING, F MILLBURN, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRIC COllIPANY, INCQR-PC-RATED, 01 NEYV YORK, It. 1., A GORPGEATION 0F NEW YORK I ELECTRIC WAVE TRANSLATION SYSTEM Application filed April 29, 192 Serial This invention relates to electr1c wave translation systems and more particularly to means for reducing the amount of power wastefully dissipated in space discharge 5 tubes thereof and the circuits connected thereto.

As is already known, it is desirable in systems utilizing three electrode space discharge tubes for transmitting power, to

maintain the anode potentials of such tubes as low as possible during that part of the cycle when a large current is flowing through the tube in order to reduce energy losses therein. The most desirable condition would be to have the tube impedance change abruptly from an infinite value to zero for each cycle of impressed waves. With this condition, loss of energy in the tube would be prevented. This result, however, can

only be approximated. In practice, al-

though the tube-impedance may be made infinite by impressing a sufiiciently large negative potential upon the control electrode, it cannot be made zero.

An object of the invention, therefore, is to obtain increased efficiency in the transmission of waves in systems of space discharge tubes by reducing the energy loss within the tubes of the system.

Another object is to impede waves of higher harmonic frequencies in the output circuit of the space discharge device, whereby waves of fundamental frequency are transmitted more efliciently.

A further object is to produce in an electric circuit connected to a space discharge device, waves of current and voltage of such form and phase that when the current through the tube is large, the voltage impressed upon the anode will be small and vice versa.

Another object is to provide an output circuit for space discharge tubes which selectively transmits the current of fundamental frequency and at the same time presents con stant non-reactive impedance to current of all frequencies supplied by the tube.

A feature of the invention relates to a series tuned circuit having a resistance in shunt connected in the output circuit of a No. 709,736. Renewed April 11, 1929.

space discharge tube to offer high impedance to waves of higher harmonic frequencies and very low impedance to waves of the fundamental frequency and so proportionedas to supplement the impedance of the other portions of the circuit whereby theimgedance thereof is maintained substantially equal for waves of all frequencies.

Another feature of the invention relates to a load circuit connected to the output electrodes of space discharge tubes, which consists of a plurality of selective elements, the individual effective impedance of which is greater for certain frequencies than for others, but the combined efi'ective impedance of which is substantially the same for a plurality of frequencies.

Another feature concerns an arrangement for modifying the reactance of a condenser and an inductance in a series tuned circuit to equalize the impedance of a connected circuit to currents of a plurality of frequencies.

A further feature concerns-a power are-- plifying system utilizing space discharge tubes whereby substantially rectangular waves of voltage and current in the output circuit of said tubes may be produced.

In general the principles of this invention may be illustrated as applied to systems of space discharge tubes. In one such system a source of waves preferably of rec tangular form, is connected to the input circuit of a space discharge tube system. Connected to the output circuit of the system there is in addition to an anti-resonant or coupled tuned circuit, a series tuned circuit having in shunt thereto a resistance. The anti-resonant or coupled circuit may in turn be coupled to any load circuit, for

example, to an-antenna or to a wire line for transmitting waves to a receiving system. For the purpose of signaling, a key may be connected in'the circuit of the source of rectangular waves for producing interruptions thereof corresponding to signals.

In this embodiment of the invention high efliciency is obtained by reduction of losses within the space discharge tubes and by impeding waves of undesired frequencies in the output circuit of the system and at the same time transmitting waves of desired frequency substantially unimpeded.

To utilize other principles of the invention space discharge tubes are arranged in a system such that the impedance thereof to currents flowing in a connected circuit is constant. This arrangement may comprise space dischargetubes connected in push-pull relation. Rectangular or any other form of waves of large amplitude as, for example, sine waves may be suppliedto the input circuit of the system to vary the impedance of the push-pull tubes abruptly from an infinite to a small finite value respectively.

There then appear, in the output circuit of the system, waves corresponding to those impressed upon the input circuit. High efiiciency is obtained in this arrangement the same as in the one just described, since the impedance of each tube is always such that with a large current flowing there through the voltage impressed thereon. is small and vice versa. By virtue of the fact that the impedance of the system, as viewed from a connected load circuit, is constant, harmonic components produced therein may be impeded without affecting the efficiency of operation of the system.

The waves produced by thesystem may be modulated in accordance with signals in a manner different from that already described by connecting to the output circuit. the anode circuit of a space discharge amplifier arranged to be controlled by a source of signals, for example, a microphone transmitter.

In the drawings, Fig. 1 illustrates a circuit embodying certain of the principles of this invention.

Fig. 2 shows certain forms of waves that may be utilized in the various circuits illustrated in-. the drawings.

Fig. 3 illustrates a radiant energy signaling system arranged to utilize the principles of this invention for obtaining high efficiency. I t

Fig. 4 shows a system similar to Fig. 3 in which the load circuit is connected to the power tubes by a capacity coupling.

Fig. 5 shows a circuit similar to Figs. 3 and 4, in which the load circuit is directly connected to theanode circuits of thezpower tubes. I

Fig. 6 illustrates a modulating amplifier arrangedto be connected to the circuits of Figs. 3 and 4.

Fig. 7 illustrates a circuit modification which may be substituted for the portions shown in the dotted lines on Figs. 1, 3, 4 and 5.

Fig. 8 represents a filter arrangement which may also be substituted for the porin series with an anti-resonant load circuit 17. A battery 18 in series with achoke coil 19 is connected to the anode and cathode of the tube to supply spacecurrent thereto.

Waves from the source 10, which preferably have a rectanglar form but may have any other form, such as indicated by Fig. 2. may be impressed upon the control electrode of tube 11 by actuating key 13. Battery 12 is provided to apply a suitable average potential to the control electrode of the tube.

It is well known that a rectangular wave of the form indicated in Fig. 2 containsa component of fundamental frequency together with a large number of components of harmonic frequencies. In the output circuit of tube 11 there will be repeated a wave. corresponding in shape to that impressed upon the control electrode, provided the impedance of the circuit connected to the tube is the same for all frequencies present therein and its reactance is zero at these frequencies.

The anti-resonant circuit 17 is tuned to the frequency ofthe fundamental component of these waves which it is desired to transmit and consequently is highly selective of and los has a high effective resistance to waves of this frequency but relatively low effective resistance to waves of the harmonic frequencies. Impedance element 14 supplements the impedance of anti-resonant -cirll cuit 17 whereby the impedance of the whole circuit is more nearly the same for waves of all frequencies. The. reactance of element 14 is complementary to that of circuit 17 and the two form a substantially non-reac- 1 1 15 tive circuit for waves, of all frequencies.

'Hence the impedance of the .Whole circuit is .equivalentto a pure resistance.

Element 14 comprises aseriestuned circuit 16 which is adjusted [to resonance at 1. the frequency of the fundamental waves. This resonant circuit, therefore, offershigh impedance to waves of all frequencies differing materially from the fundamental. A resistance v15 whichis connected in shuntto 1.

resonant circuit 16, assists. in imparting to frequencies which are impeded by the resonant circuit 16. This resistance serves, in addition, to dissipate the energy stored in the inductance coil of the resonant circuit 16 whereby this energy is prevented from setting up transient surges in the circuit at the instant the tube resistance becomes infinite.

In considering the operation of the circuit of Fig. 1, it may be looked upon as analogous to an arrangement comprising a battery in series with an interrupter and a pure resistance. The wavesfrom source 10 vary the impedance of tube 11 in a manner cor responding to the action of the interrupter. since this impedance changes abruptly from an infinite to a small finite value. The impedance of the circuit connected to the out put electrodes of the tube 11 is equivalent to the pure resistance as already explained, since the reactance of the element 14 is complementary to that of the element 17 and the total reactance of the circuit for all frequencies present therein is zero. There will be produced, therefore, in a circuit of this character, waves having a form determined by the manner of variation of the impedance of the tube by source 10. These waves, under the conditions described, are of rectangular form and contain a large number of harmonic components. Tuned circuit 16 impedes the harmonic components of current in the output circuit so that they are caused to pass through resistance 15 and dissipate their energy therein. On the other hand, the waves of fundamental frequency are unimpeded by circuit 16 and the energy thereof is available at resonant circuit 17.

If waves of a different form such, for example, as sinusoidal waves are supplied by source 10, then the resistance 60 is preferably connected in the input circuit of tube 11 by opening switch 61. The efiect of this resistance is such as to permit large negative potentials to be impressed upon the grid of the tube, but to prevent large positive potentials from being impressed thereon. When the grid is positive and current flows in the grid circuit, the drop of potential along resistance 60 reduces the potential available at the grid, whereas when the grid is negative no current fiows in the grid circuit, and consequently, the whole potential from source 10 is available on this electrode. The result is that the tube impedare connected by transformer 20 to the input circuit of a space discharge amplifier 21 comprising three-electrode space discharge tubes 22 and 23 in balanced or push-pull arrangement. The terminals of the secondary winding of transformer 20 are connected respectively to the control electrodes of tubes 22 and 23. The mid-point of this winding is connected through a polarizing battery 24 to the filaments of the tubes. The filaments are arranged to be heated by means of a common battery 25. Another common battery 26 is connected in series with the switches 28 and 29 to supply energy to the anode circuits of tubes 22 and 23 by connection to the mid-point of the primary winding of transformer 27 A load circuit 30 is connected to the secondary winding of transformer 27 and includes anti-resonant circuit 17 in series with series resonant circuit 15. Anti-resonant circuit 17 is inductively coupled to coil 31 connected in series to antenna 32 and ground.

WVaves supplied from source 10 through transformer 20 are such as to vary the impedance of tubes 22 and 23 alternately from infinite to a small finite value, that is, when the impedance of tube 22 is infinite the impedance of tube 23 is small and vice versa. Hence the total impedance of the two tubes is substantially constant in valve. Vaves corresponding to those supplied by source 10 are consequently repeated in the output circuits connected to the anodes and cathodes of tubes 22 and 23. These waves are transmitted through transformer 27 to the load circuit 30. Since these Waves are of substantially rectangular form, there are present in the load circuit 30 voltage waves of fundamental and harmonic frequencies. The series resonant circuit 16 has high impedance to components of all frequencies other than the fundamental and consequently prevents the flow of currents of these frequencies in the load circuit. The resistance 15 is omitted in this instance since on count of the constancy of impedance of the combined tubes there is no tendency for transient effects to be producedin the load circuits. The current waves present in the load circuit therefore are substantially of a sine wave form'and the energy of these waves is transmitted from the resonant circuit 17 through transformer 31 to antenna 32. The circuit of Fig. 3 operates at high efiiciency, since losses in the tubes 22 and 23 are substantially eliminated by the manner in which the impedance of the tubes is variedand energy losses produced by harmonic components of current are prevented by the tuned circuits 16 and 17 connected in the load circuit 30. V

In Fig. 4, a circuit similar to that of Fi 3 is shown in which the load circuit 30 1s coupled to the output circuit of tubes 22 and 23 by means of condensers and 36.

being reduced by the series tuned circuit to such a small amount that there is no objection to its being dissipated in tubes 22 and 23.

The circuit here shown produces substantially a sine wave of current in the output circuit 30, just as in Fig. 3, since harmonic components are substantially suppressed by the seriesresonant circuit 16. A full sine wave of current is produced because tubes 22 and 23 allow the respective halves of each cycle of impressed waves to be effective in producing current in the output circuit.

In the circuit of Fig. 5, tubes 22 and 23 have their output circuits directly connected in parallel to the load circuit 30 comprising anti-resonant circuit 17 and series tuned circuit 16. The anode of tube 22 connects to the cathode of tube 23 and the anode of tube 23 connects to the cathode of tube 22 in series with divided battery 33.

The operation of this circuit is substantially the same as that of Fig. 4. \Vaves, preferably rectangular shaped, are impressed on the control electrode circuits of tubes 22 and 23 through transformer 37 whereby similarly shaped waves of current are produced in the respective output circuits of the tubes. Transformer 37 has its winding so arranged that the potentials supplied to the tube input circuit by waves from source 10 cause current to be produced in the output circuit of tube 22 during one half cycle of the impressed waves, whereas dur ing the opposite half cycle of the impressed waves they cause current to be produced in the output circuit of the tube 23. That is, during alternate half cycles tube 22 transmits impulses of current from battery 33 through the branch 17, 16 in one direction and during theintervening half cycles tube 23 transmits current from battery 33' through branch 17, 16 in the opposite direction. By the action of these combined currents in load circuit 30 in conjunction with the impedance of series resonant circuit, 16, there is produced in the load circuit a substantial sine wave current. By the use of waves of rectangular form, the efficiency of the system is increased by virtue of' the fact that when the current in the load circuit is large the electromotive force across the tubes is small whereby the power dissipated in the tubes is reduced as already explained.

In Fig. 6 is shown an amplifier 50 arranged to be controlled by a source of waves 51. The source 51 may, for example, be an ordinary microphone transmitter. By

means of a transformer 53 the transmitter local circuit is coupled to the input circuit of three-electrode space discharge tube 52, which input circuit is connected to the cathode and control electrode of the tube. Connected to the anode and cathode of the tube is a space current circuit that includes the battery 54 and choke coil 55, the latter being shunted by a bypass condenser 58 for signal or other alternating waves. By connecting terminals 56 and 57 to terminals 56 and 57 of Figs. 3 and 4 and by moving switches 28 and 29 to the contacts connected to these terminals the amplifier of Fig. 6 may be utilized to produce modulation of the waves in circuits 30 in accordance with speech. When operating in this manner, the key 13 is left closed.

In Fig. 7 the series resonant circuit 16 shunted by resistance 15 is connected .to the terminals of the secondary winding of transformer 40. The arrangement shown in this figure may be substituted for the portion included within the dotted lines in any of the Figs. 1, 3, 4, or 5. The winding of transformer 40 in the tube circuit is considered to be the primary winding. Transformer 40 is designed to have a ratio of primary to secondary turns less than unity for the purpose of multiplying the ratio of capacity to inductance in series resonant circuit 16 whereby smaller reactance elements may be used in this circuit. The arrangement of Fig. 7 functions in the above named circuits substantially the same as the elements which it replaces therein.

The modification shown in Fig. 8 comprises a resonant circuit including a filter 41 in series with a condenser 42. This organization is arranged to perform substantially the same function as element 14 of Figs. 1 and 3 and the series resonant circuit 16 of Figs. 4 and 5 and may be substituted for the portion included within the dotted lines in any of these circuits. By means of the filter, the impedance characteristics of the resonant circuit of which it forms a part may be designed to have any desired form in order to supplement that of the anti-resonant circuit.

Although this invention has been decribed in connection with certain preferred forms of radiant energy transmitting systems, it will be apparent that it is susceptible of application to numerous other circuits and it is intended therefore, that it shall be limited only by the scope of the appended claims.

The operation of a discharge device to secure high efficiency by confining the anode current flow to alternate half cycles only of the applied wave is disclosed and broadly claimed in my prior Patent No. 1,712,994, dated May 14, 1929, entitled Oscillation production What is claimed is:

1. In an electric energy translating sys tem a variable impedance device, means for alternately varying the impedance of said device abruptly from an infinite to a very small finite, value, and an electric circuit controlled by said impedance device, said circuit comprising inductive and capacitive elements arranged in resonant and anti-resonant relation and respectively complementary to provide a non-reactive path for a band of frequencies.

2. In an electric energy translation system, a source of waves to *be transmitted,

a load circuit on which said waves are to be impressed, and-a circuit coupling said source to said load circuit, said latter circuit including frequency selective means for impressing a band of frequencies on said load circuit, other frequency selective means in said coupling circuit in series between said source and said load and including resistance, for making the total impedance presented to said source substantially constant and independent of frequency.

3. In a signaling system, a source of sig-' nal waves, a circuit comprising a plurality of variable impedance devices arranged in balanced relation supplied with said waves, a load circuit coupled to said first named circuit, said load circuit comprising a selective element, a transmitting conductor coupled to said selective element, and means in said load circuit cooperating with said selective element to render said load circuit substantially nonreactive.

4. In an electric energy translation system, a three-electrode space discharge tube, a source of waves and means for causing said waves to vary the impedance between two of the electrodes of said tube in accordance with signals, a circuit including the impedance of said tube, said circuit comprising a plurahty of selective elements, one of said elements being selective of a desired frequency, the other of said elements being also selective of the desired frequency, and means associated with one of said elements for dissipating the energy of undesired frequencies.

5. In an electric wave translation system, a plurality of three-electrode space dlscharge devices, means for varying the indlvidual impedance of said devices alternately from infinite to small finite values successively,

an electric circuit including said devices arranged to have constant lmpedance, and selective elements assoclated wlth sald circuit for transmitting desired waves and suppressing undesired waves, the combined re- Waves, means to increase the efiiciency of said amplifier comprising a load circuit having selective elements therein offering uniform impedance for transmitting a desired band of frequencies.

7. In a radiant energy signaling system, a source of waves of rectangular form, a plurality of three electrode space discharge tubes, a common input circuit connected to the control electrodes of said tubes and impressed with waves from said source, an output circuit connected to the anodes of said tubes, and a load circuit supplied with energy from said output circuit, said load circuit having substantially equal impedance to waves within a band of frequencies.

8. A radiant energy signaling system which comprises a source of waves of rectangular form, a space discharge amplifier comprising an input circuit and an output circuit, said input circuit being impressed with waves from said source, and a load circuit coupled to said output circuit comprising a network uniformly selective within a band of frequencies but having high effective resistance to waves of undesired frequencies, said network comprising means for dissipating the energy of said undesired waves.

9. In a high frequency signaling system, a space discharge amplifier, means for producing in an output circuit of said amplifier waves of substantially rectangular form, a load circuit comprising a plurality of resonant circuits, said load circuit having zero reactance to waves within a band of frequencies and high resistance to waves of undesired frequencies.

10. In a radiant energy signaling system, a pair of three electrode space discharge tubes having symmetrical input circuits and symmetrical output circuits, said input circuits being impressed with waves of rectangular form whereby waves of similar form are produced in said output circuits, a space discharge amplifier connected to said output circuits and arranged to supply energy to the anode circuits of said space discharge tubes, and means comprising a source of signals for controlling the amount of energy supplied, an antenna, a closed circuit coupled to said antenna and to said symmetrical output circuits, said closed circuit comprising means for equalizing the impedance thereof to waves of a plurality of frequencies whereby the elliciency of transmission of certain of said waves is increased.

11. In combination, a plurality of space discharge tubes each comprising a cathode,

an anode and a control electrode, means for causing the impedance of the discharge paths of said tubes to change substantially instantly from an infinite value to a very small finite value during alternate half cycles of an impressed wave, and means con nected to the cathodes and anodes of said tubes whereby the current components of a band of frequencies are transmitted with zero reactance and current components of undesired frequencies are dissipated externally of said tubes.

12. In combination, an amplifier impressed with waves containing components of fundamental and harmonic frequencies, said amplifier comprising three electrode space discharge tubes arranged to utilize both half cycles of the impressed waves, an output circuit for said tubes including the discharge path thereof, and means for causing the space path of one'of said tubes to assume an infinite value of impedance and a small finite value of impedance successively during alternate cycles of impressed waves said output circuit comprising a non-reactive path for a band of frequencies.

13. In combination, an amplifier in;- pressed with waves containing components of fundamental frequencies, said amplifier comprising three electrode space discharge tubes arranged toutilize both half cycles of the impressed waves, an output circuit for said tubes comprising the space path thereof, andmeans comprising a series resonant circuit shunted by a high resistance to cause the energy of harmonic components to be dissipated externally of said space paths.

14:. In an amplifier comprising a three electrode space discharge tube, means for causing the voltage across the space path electrodes of said tube to be small when'the current flowing between said electrodes is large which comprises a resonant circuit having in shunt thereto a high resistance, the input circuit of said space discharge amplifier having impressed thereon waves of rectangular form, a load circuit therefor, means anti-resonant at the fundamental frequency of the impressed waves connected to said load circuit whereby a substantially sine wave of current of fundamental frequency is produced in said load circuit.

15. A space discharge amplifier, means for impressing thereon constant amplitude waves of rectangular form, aload circuit for said amplifier, said load circuit furnishing a path of zero reactance for a band of frequencies and an antenna coupled to said load circuit, and means for impressing voltage waves varying in accordance with speech on said load circuit whereby the amplitude of current waves therein is caused to undergo similar variations and whereby speech modulated waves are transmitted from said antenna.

16. In a signaling system, a source of constant amplitude waves of rectangular form, a, space discharge amplifier impressed with said waves, said amplifier comprising an output circuit, means in said output circuit comprising a second space discharge amplifier controlled by a source of signals for modulating waves produced in said output circuit, an antenna, a load circuit coupled to said output circuit and to said antenna, the impedance of said load circuit being de; signed to be substantially the same for waves of all: frequencies present therein, and a resistance connected to said load circuit, said resistance being substantially greater in value than the impedance of said first named space discharge amplifier.

17. A space discharge amplifier comprising a pair of space discharge tubes each comprising a cathode, an anode and a control electrode, a source of rectangular sh ped waves, means for impressing the energy of said waves upon the control electrodes of said tubes, a source of space cur-. rent connected in series to the space paths of said discharge tubes, and; a load circuit comprising a plurality of. selective circuits,

said selective circuits being adjusted to substantially suppress the harmonic frequency. components of a band of waves flowing therethrough, thereby causing the waves within the band. to have. a sine wave form.

18. In a signaling system, a source of waves of rectangular. form, means for impressing said waves upon the input circuit of a space discharge amplifier comprising three electrode space discharge tubes ,arranged in push-pull relation, a key for controlling application of said waves to saidmput circuit, a load circuit for saidamplifier and; an antenna coupled thereto for radiating energy therefrom, said load circuit being arrangedin energy transferrelation with said amplifierby meansof inductive coupling, and means between; the output electrodes of said tubes and said antennacomprising resonant and anti-resonant elements providing a substantially non-rea tive resistance to waves of a bandof frequencies including the principal frequency components represented in the waves, im.- pressed upon the input circuit.

19. In combination, a space discharge prising a load circuit having means for impeding Waves of the harmonic frequencies, said means comprising a series resonant circuit in shunt to a resistance and the secondary of a transformer, the primary of which transformer is connected directly in said load circuit.

21. In combination with a space discharge amplifier comprising an input circuit controlled by a source of rectangular waves of constant amplitude and an output circuit, a load circuit containing current components of fundamental and harmonic frequencies, means comprising a plurality of clifferent reactance elements to impede said components of harmonic frequencies and means to multiply the reactance of said elements.

22. In an electric energy translation system, a source of waves to be transmitted, a transmission circuit on which said waves are to be impressed, and a circuit coupling said source to said transmission circuit and including reactive elements for impressing a selected band of frequencies on said transmission circuit, and other elements comprising reactance and resistance in said coupling circuit, said latter elements neutralizing the effect on said coupling circuit as a Whole of said first mentioned reactive elements and compensating for variations in resistance with frequency, of said first mentioned elements and transmission circuit.

23. In an electric energy translation system, a circuit including a source of voltage and a circuit control element, a transmission circuit, means for varying the impedance of said circuit control element abruptly between very low and very high values Whereby steep-fronted impulses are transmitted through it, said circuit including reactance elements for selectively impressing on said transmission circuit the fundamental frequency components of said impulses while suppressing the higher harmonics thereof, said circuit also including other elements comprising reactance and resistance proportioned to supplement the impedance of the first mentioned reactance elements and transmission circuit whereby the impedance of the circuit is maintained substantially equal for waves of all frequencies.

In witness whereof, I hereunto subscribe my name this 28th day of April, A. D.

RAYMOND A. HEISING. 

